The present invention is concerned with an entropy coding concept for coding media content such as video or audio data.
Many audio and video audio codecs are known in the art. Generally, these codecs reduce the amount of data necessitated in order to represent the media content such as audio or video, i.e. they compress the data. However, the demands imposed onto these codecs are not limited to achievement of high compression efficiency. Rather, codecs tend to be specialized for certain application tasks. Accordingly, in the audio field, there are audio codecs specialized for speech coding while others are specialized for coding music. Moreover, in some applications, the coding delay is critical and, accordingly, some of the codecs are specialized for low delay. Beyond this, most of these codecs are available in different levels of complexity/effectiveness. That is, some of these levels are for lower coding complexity at the cost of lower coding efficiency. The H.264 video coding standard, for example, offers a baseline profile and a main profile. Primarily, these coding profiles differ from each other in activation/deactivation of certain coding options/gadgets such as the availability/absence of SBR in the audio coding field and the availability/absence of B frames in the video coding field. Beyond this, a considerable part of the complexity of these media codecs relates to the entropy coding of the syntax elements. Generally, VLC entropy coding schemes tend to be less complex than arithmetic coding schemes while the latter show a better coding efficiency. Accordingly, in the H264 standard, context adaptive binary arithmetic coding (CABAC) is available only in the main profile rather than the base line profile. Obviously, base line profile conform decoders may be configured less complex than main profile conform decoders. The same applies for the encoders. Since handheld devices including such decoders and/or encoders suffer from a limited energy availability, the baseline profile has the advantage over the main profile with regard to the lower complexity. Main profile conform de/encoders are more complex not only because of the more complex arithmetic coding scheme, but also because of the fact that these main profile conform de/encoders have to be backwards compatible with baseline profile conform data streams. In other words, the increased complexity is due to the arithmetic coding scheme adding up to the complexity stemming from the lower complexity variable length coding scheme.
In view of the above, it would be favorable if there would be a coding concept which allows for a more efficient scalability of the ratio of the codex between coding complexity on the one hand and coding efficiency on the other hand.